The present disclosure relates to a bump manufacturing method, and more particularly, to a bump manufacturing method that provides varied shapes of bumps by adjusting a reflow condition.
Semiconductor devices, particularly semiconductor light emitting devices, may be manufactured as packages or modules. Recently, semiconductor devices are being manufactured more frequently as modules for a chip on board (COB) scheme that contains a module directly on a board, as opposed to being manufactured as packages. Accordingly, semiconductor device modules manufactured for the COB scheme may reduce costs for manufacturing the packages, and may improve heat radiation by reducing a heat transfer path.
A technology has been developed that manufactures the semiconductor device modules as flip chip on module (FCOM) that contains a semiconductor device on a module board in a form of a flip chip. Accordingly, when semiconductor device modules are manufactured for the COB scheme, the semiconductor device modules may be manufactured as FCOM and thus, wire-bonding may not be used to provide an electrical connection between the semiconductor device and the module board. The FCOM may include a semiconductor device based on a flip chip scheme and thus, the semiconductor device may be densely mounted on the module board, and a size of the module may be reduced.
To embody the FCOM, a process that forms a bump on an electrode pad included in the semiconductor device may be used. The bump forming process may be performed, for example, based on a plating scheme or a screen-printing scheme.
The plating scheme may form bumps at fine pitches, and may manufacture varied sizes of bumps. However, as manufacturing costs are high, a price competitiveness of the semiconductor device module may be adversely affected.
Conversely, although the screen-printing scheme has a simple manufacturing process and relatively lower manufacturing costs, the screen-printing scheme may have difficulty in providing fine pitches among the bumps. However, the screen-printing scheme may be appropriate for a light emitting device that does not need the fine pitches among bumps. When bumps are formed based on the screen-printing scheme, a semiconductor device on which the bumps are formed may be reflowed.
FIG. 1 illustrates a conventional shape of a bump 12 that is reflowed through a reflow process.
Referring to FIG. 1, the bump 12 may be spread over a whole electrode pad 11 included in a semiconductor device 10, through a reflow process, and a surface of the bump becomes curved as a surface energy decreases. For example, a shape of a bonded surface of the bump 12 may be determined based on the electrode pad 11, and the bump 12 may have a convex surface.
A shape of the bump 12 may vary based on a product to which the semiconductor device 10 is to be applied. To change the shape of the bump 12 of FIG. 1 to a globular shape, the electrode 11 may be manufactured in a circular shape. However, in this instance, it is still difficult to manufacture the bump 12 in a complete globular shape.
Therefore, to change the shape of the bump 12 to a globular shape, an additional process or device for modifying the shape of the bump 12 during the reflow process may be needed.